The clinical role of autologous bone marrow transplantation in the treatment of cancer is uncertain. In 1975 we initiated an autologous transplantation program which demonstrated the feasibility of rescue from lethal cytotoxic therapy in leuekemia and in selected solid tumors. A few long-term disease-free survivors resulted from this drastic therapy. The major clinical issues to be addressed area: the role of high dose cytoreductive therapy with autologous bone marrow rescue for intensification of remission in leukemia, the role of monoclonal antibodies for elimination of leukemic cells contaminating the collected bone marrow. Basic biological questions arising from the clinical programs are addressed in the individual projects: 1) biologic and biochemical specificity of cell surface markers as defined by monoclonal antibodies on human leukemic cells; 2) the characterization of the leukemic cell population forming colonies in vitro; 3) the characterization and interaction of hemopoietic and immunologic cell recovery defined by a variety of in vitro cell culture methods following cryopreservation and transplantation. The general aims are to continue to elucidate and to expand on the role of autologous marrow transplantation in leukemia and to gain insight in the regulation of normal and abnormal hemopoiesis.